The MGM Grand has, over the last several years, become Manny Pacquiao’s home turf. When he has fought in the big green building – or, for that matter, in the gold building across the street called the Mandalay Bay – he has been the undisputed fan favorite, the casino transformed temporarily into an annex of Manila.

But whether he wants one or not, Pacquiao now has a roommate, and one who is clearly bucking to evict him entirely. It was first notable the last time he fought Juan Manuel Marquez, when the cries of “Si se puede” threatened to drown out the roars of Pacquiao’s traveling support, and when the announcement that the Filipino had won a majority decision was greeted not with roars of relief but a cascade of disapproving boos.

The scene was repeated at Friday’s weigh-in for Pacquiao-Marquez IV: Pacquiao, as always, had plenty of support among the 6,000 or so assembled in the Grand Garden Arena. But Marquez, it seemed, had more. It isn’t so much that Pacquiao’s fan base is shrinking, more that Marquez’ fan base is growing.

And so, for that matter, is Marquez. He weighed in four pounds lighter than Pacquiao, but he looked substantially larger. His chest appeared several shirt sizes bigger than at any time in his career, and his biceps bulged as he flexed.

Marquez also showed an unwavering intensity. Pacquiao smiled, Marquez stared. Pacquiao talked of wanting a good fight, Marquez spoke of a war.

Perceptions mean nothing once the punches start flying. But right now, one day before the bell rings, there is a growing sense that the tide may be turning in this long-running rivalry.